Effects of misalignment on the structure characteristics of bump-type foil bearings: a comparison between experimental and theoretical results
Abstract
Purpose
The purpose of this paper is to investigate the effects of misalignment on the static and dynamics characteristics of bump-type foil bearings (BFBs). High-speed and high-temperature oil-free turbomachinery can be realized with the use of gas foil bearings (GFBs). GFBs have a flexible supporting structure; thus, they can tolerate a higher degree of misalignment compared with rolling element bearings.
Design/methodology/approach
A test rig for GFBs has been developed to measure the effects of misalignment on the structure characteristics of bump-type foil bearings. The link-spring model, which is the foil structure model presented previously by the authors, is used as a basis in the present study to predict the static and dynamic performances of the foil structure. In general, predictions of the dynamic characteristics exhibit good agreement with the measurements acquired from the dynamic load tests.
Findings
Results from the static tests show that GFBs develop high stiffness when the misalignment angle increases. Moreover, the dynamic characteristics of GFBs are identified by considering the test bearing supported by a non-rotating shaft as a one-degree-of-freedom system. The results indicate that the dynamic characteristics of GFBs strongly depend on excitation frequency and excitation amplitude because of the variation in the dynamic friction force within the foil structure. The structural stiffness and equivalent viscous damping increase with an increase in the misalignment angle.
Originality/value
The present study focuses on the misalignment of GFBs and investigates experimentally the effects of misalignment on the structure characteristics of GFBs.
Keywords
Acknowledgements
This work was supported by National Science Foundation of China under Grant No. 51305131 and International Cooperation Project of Hunan Provincial Science and Technology Department under Grant No. 2013WK2014 and the Specialized Research Fund for State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body under Grant No. 71275001. The authors would like to thank Dr H. Houjoh and Dr S. Matsumura of Tokyo Institute of Technology for their valuable discussion on the construction of the test rig.
Citation
Feng, K. and Zhao, X. (2015), "Effects of misalignment on the structure characteristics of bump-type foil bearings: a comparison between experimental and theoretical results", Industrial Lubrication and Tribology, Vol. 67 No. 4, pp. 370-379. https://doi.org/10.1108/ILT-09-2013-0101
Publisher
:Emerald Group Publishing Limited
Copyright © 2015, Emerald Group Publishing Limited